<div>myc05-ngstyle works!</div>
<h3>指令: [ngStyle]</h3>
<button [ngStyle]="myBtnStyle" (click) = "changeStyle()">更换按钮颜色1</button>

<h3>指令: [ngClass]</h3>
<button [ngClass]="myBtnClass" (click) = "changeClass()">更换按钮颜色2</button>

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